Washington (CNN) – A majority of Muslims (57%) in Russia’s North Caucasus – including Chechnya, Dagestan and five other Russian jurisdictions – are either “very concerned” or “somewhat concerned” about religious extremist groups in their country, according to a Pew Research Center survey.

That number is higher than Russia as a whole, where more than four-in-10 Muslims in the country express the same level of concern.

This region of the world, particularly Chechnya and Dagestan, has been in the news recently because the suspects in last week’s Boston Marathon bombing – Dzhokhar Tsarnaev, the younger brother who is still alive, and Tamerlan Tsarnaev, the older brother who died in a shootout last week – had familial ties to the region.

The two brothers were born in Kyrgyzstan, where 62% of Muslims told Pew they were very or somewhat concerned about extremism in the central Asian country.

The CNN Belief Blog covers the faith angles of the day's biggest stories, from breaking news to politics to entertainment, fostering a global conversation about the role of religion and belief in readers' lives. It's edited by CNN's Daniel Burke with contributions from Eric Marrapodi and CNN's worldwide news gathering team.